Tino Schwarze wrote:
> 
>> A missing member doesn't bother raid1 at all.
> 
> It bothered mdadm --monitor! It always complained, there seemed to be no
> way to fix it, so monitoring became useless.

You can just peek at /proc/mdstat once in a while.

>> The way I do it is to create a raid1 with 3 members, one specified as 
>> 'missing'.  Then once a week I put in a disk and 'mdadm --add ...' the 
>> partition to the array.  When it finished mirroring (a little over 2 
>> hours for a 750 gig SATA), I momentarily stop backuppc and unmount the 
>> array so the filesystem is clean, then fail and remove the partition and 
>> rotate that disk offsite.  That way I always have a pair of mirrored 
>> disks locally and one or two slightly out of data offsite.
> 
> Bad luck. My backuppc file system is already at 900 GB and located in an
> LVM volume which is on a HW RAID5 of 3x750 GB SATA disks.

You can get 1 TB SATA drives these days - and trayless hot-swap enclosures.

> I wonder
> whether something similar would be possible with LVM snapshots or
> somesuch... but I suppose, I would pay yet another performance penalty.

Theoretically yes, but I've never seen enough documentation on 
recovering a corrupted LVM to trust my ability to do it.   If I ever 
have time to build something that has zfs (solaris, freebsd, or maybe if 
I wait long enough, OSX), I'd like to try its snapshot send/receive 
facility.

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com


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